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🔗 Mathematics

The Trachtenberg system is a system of rapid mental calculation. The system consists of a number of readily memorized operations that allow one to perform arithmetic computations very quickly. It was developed by the Russian Jewish engineer Jakow Trachtenberg in order to keep his mind occupied while being in a Nazi concentration camp.

The rest of this article presents some methods devised by Trachtenberg. Some of the algorithms Trachtenberg developed are ones for general multiplication, division and addition. Also, the Trachtenberg system includes some specialised methods for multiplying small numbers between 5 and 13.

The section on addition demonstrates an effective method of checking calculations that can also be applied to multiplication.

🔗 Philosophy 🔗 Philosophy/Logic

Bulverism is a term for a rhetorical fallacy that combines circular reasoning with presumption or condescenscion. The method of Bulverism is to "assume that your opponent is wrong, and explain his error." The Bulverist assumes a speaker's argument is invalid or false and then explains why the speaker came to make that mistake, even if the opponents's claim is actually right, attacking the speaker or the speaker's motive. The term Bulverism was coined by C. S. Lewis to poke fun at a very serious error in thinking that, he alleges, recurs often in a variety of religious, political, and philosophical debates.

Similar to Antony Flew's "subject/motive shift", Bulverism is a fallacy of irrelevance. One accuses an argument of being wrong on the basis of the arguer's identity or motive, but these are strictly speaking irrelevant to the argument's validity or truth.

🔗 Aviation 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/Military science, technology, and theory 🔗 Aviation/aircraft

In aerobatics the Cobra maneuver, also known as just the Cobra, is a dramatic and demanding maneuver in which an airplane flying at a moderate speed suddenly raises the nose momentarily to the vertical position and slightly beyond, before dropping it back to normal, effectively making the plane a full body air brake.

The maneuver relies on the ability of the plane to be able to quickly change alpha which momentarily stalls the plane without overloading the airframe and powerful engine thrust to maintain approximately constant altitude through the entire move. It is an impressive maneuver to demonstrate an aircraft's pitch control authority, high alpha stability and engine-versus-inlet compatibility, as well as the pilot's skill.

Although the maneuver is mainly performed at air shows it has use in close range air combat as a last ditch maneuver to make a pursuing plane overshoot. There is currently no widely spread or readily available evidence of the Cobra being used in real combat, although, there are records of it being used during mockup-dogfights and during border protection.

🔗 History 🔗 Telecommunications 🔗 Radio 🔗 Astronomy

The Arecibo message is a 1974 interstellar radio message carrying basic information about humanity and Earth sent to globular star cluster M13. It was meant as a demonstration of human technological achievement, rather than a real attempt to enter into a conversation with extraterrestrials.

The message was broadcast into space a single time via frequency modulated radio waves at a ceremony to mark the remodeling of the Arecibo radio telescope in Puerto Rico on 16 November 1974. The message was aimed at the current location of M13 some 25,000 light years away because M13 was a large and close collection of stars that was available in the sky at the time and place of the ceremony. The message forms the image shown here when translated into graphics, characters, and spaces.

🔗 Mathematics

The 100 prisoners problem is a mathematical problem in probability theory and combinatorics. In this problem, 100 numbered prisoners must find their own numbers in one of 100 drawers in order to survive. The rules state that each prisoner may open only 50 drawers and cannot communicate with other prisoners. At first glance, the situation appears hopeless, but a clever strategy offers the prisoners a realistic chance of survival. Danish computer scientist Peter Bro Miltersen first proposed the problem in 2003.

🔗 Pharmacology 🔗 Dentistry

A caries vaccine is a vaccine to prevent and protect against tooth decay. Streptococcus mutans (S. mutans) has been identified as the major etiological agent of human dental caries. The development of a vaccine for tooth decay has been under investigation since the 1970s. In 1972, a caries vaccine was said to be in animal testing in England, and that it would have begun human testing soon. However, intrinsic difficulties in developing it, coupled with lack of strong economic interests, are the reasons why still no such vaccine is commercially available today. Several types of vaccines are being developed at research centres, with some kind of caries vaccines being considered to diminish or prevent dental caries' impact on young people.

🔗 Germany 🔗 Military history 🔗 Crime 🔗 Politics 🔗 Guild of Copy Editors 🔗 Military history/World War II 🔗 Military history/German military history 🔗 Politics/Fascism 🔗 Military history/European military history

From 1933 to the end of the Second World War, high-ranking officers of the Armed Forces of Nazi Germany accepted vast bribes in the form of cash, estates, and tax exemptions in exchange for their loyalty to Nazism. Unlike bribery at lower ranks in the Wehrmacht, which was also widespread, these payments were regularized, technically legal and made with the full knowledge and consent of the leading Nazi figures.

🔗 Germany 🔗 Anthroponymy

Kevinism and Chantalism jokingly describe the tendency of parents in German-speaking areas to name their children with what appears to them to be unusual, exotic-sounding first names.

🔗 Computing

Netpbm is an open-source package of graphics programs and a programming library. It is used mainly in the Unix world, where one can find it included in all major open-source operating system distributions, but also works on Microsoft Windows, macOS, and other operating systems.